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285 results on '"Bartley, Jonathan K."'

4. A Comparison of Monoglyceride Production from Microalgaelipids and Rapeseed Oil Catalyzed by Metal Oxides.

Author

Ferreira, Gabriela F., Ríos Pinto, Luisa F., Filho, Rubens Maciel, Fregolente, Leonardo V., Hayward, James S., and Bartley, Jonathan K.

Subjects
ESSENTIAL fatty acids, RAPESEED oil, UNSATURATED fatty acids, HETEROGENEOUS catalysis, METALLIC oxides
Abstract

This manuscript reports for the first time a heterogenous catalytic route to monoglycerides (MAGs) from microalgal oil. Microalgae is an important biomass source with high‐value applications, such as food ingredients with essential fatty acids. To date, the glycerolysis of microalgae has only been investigated for a microbial oil (Schizochytrium sp.) using enzyme catalysis. However, the use of enzymes on a large scale is currently economically impeditive and requires highly selective lipases. In this study, metal oxides were screened and the reaction conditions optimized for rapeseed oil. The optimized conditions were then used to investigate the production of MAGs from Scenedesmus sp. microalga. The most promising catalyst was found to be MgO/KOH, which gave a 44 % yield. Comparing two reaction systems (low temperature 70 °C/atmospheric pressure and high temperature at 200 °C/20 bar), it was found that the latter has a superior performance. Due to the stability of the product in air, the presence of an inert atmosphere is essential to achieve high yields. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Designing Heterogeneous Catalysts for Microwave Assisted Selective Oxygenation.

Author

Sun, Jia, Hayward, James S., Barter, Michael, Slocombe, Daniel R., and Bartley, Jonathan K.

Subjects
DIELECTRIC loss, HETEROGENEOUS catalysis, MICROWAVE heating, METAL catalysts, TECHNOLOGICAL innovations
Abstract

Microwave dielectric heating is an emerging technology in heterogeneous catalysis. However, catalyst design in this field is not as well developed as when conventional heating is used. In this study the selective oxidation of propene to acrolein has been used as a model reaction to understand the how the properties of bismuth mixed metal oxide catalysts can be tuned for use in microwave assisted catalysis. The role of the dielectric properties, that are crucial to enable the catalyst to be heated in the microwave electric field, were determined using cavity perturbation methods. Catalysts with a very high loss tangent reached high temperatures leading to combustion products, whereas materials with a low loss tangent could not be heated and were inactive. Bi2MoO6 and BiVO4 both showed promising performance during an initial screening and were investigated further. For Bi2MoO6, a partial substitution of molybdenum with vanadium resulted in the formation of Bi1−X/3V1−xMoxO4, with a decrease in particle size and dielectric loss tangent, and the highest rate of acrolein production was found when x=0.6 at 15 W microwave power. Higher microwave power resulted in thermal runaway which decreased the activity of the catalyst. [ABSTRACT FROM AUTHOR]

Published
2024
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10. The Antisolvent Precipitation of CuZnOx Mixed Oxide Materials Using a Choline Chloride-Urea Deep Eutectic Solvent.

Author

Wallace, William T., Hayward, James S., Marsh, Amy R., and Bartley, Jonathan K.

Subjects
PRECIPITATION (Chemistry), SURFACE defects, ZINC oxide, CHOLINE chloride, COPPER chlorides
Abstract

Metal oxides have applications in a variety of different fields, and new synthesis methods are needed to control their properties and improve their performance as functional materials. In this study, we investigated a low-cost antisolvent precipitation method using a choline chloride-urea deep eutectic solvent to precipitate CuZnOx materials using water as the antisolvent. Using this methodology, the metal oxide materials can be precipitated directly from the deep eutectic solvent without the need for a high-temperature calcination step that can lead to a reduction in defects and surface area, which are important properties in applications such as catalysis. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Stable amorphous georgeite as a precursor to a high-activity catalyst

Author

Kondrat, Simon A., Smith, Paul J., Wells, Peter P., Chater, Philip A., Carter, James H., Morgan, David J., Fiordaliso, Elisabetta M., Wagner, Jakob B., Davies, Thomas E., Lu, Li, Bartley, Jonathan K., Taylor, Stuart H., Spencer, Michael S., Kiely, Christopher J., Kelly, Gordon J., Park, Colin W., Rosseinsky, Matthew J., and Hutchings, Graham J.

Published
2016
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20. Perovskite Supported Catalysts for the Selective Oxidation of Glycerol to Tartronic Acid.

Author

Evans, Christopher D., Bartley, Jonathan K., Taylor, Stuart H., Hutchings, Graham J., and Kondrat, Simon A.

Subjects
CATALYST supports, PEROVSKITE, ACID catalysts, OXIDATION, GLYCERIN, NANOPARTICLES, LACTIC acid
Abstract

Exceptional selectivity of LaMnO3 perovskite supported Au catalysts for the oxidation of glycerol to the dicarboxylate tartronic acid is reported. Through using monometallic Au, Pt or bimetallic Au:Pt nanoparticles the tartronic acid yield could be altered significantly, with a maximum yield of 44% in 6 h with Au/LaMnO3 and 80% within 24 h. These LaMnO3 supported catalysts were compared with conventionally TiO2 supported catalysts, which at comparable reaction conditions produced lactic acid, via a dehydration pathway, in high yield and a maximum tartronic acid yield of only 9% was observed. The LaMnO3 catalysts produced minimal lactic acid regardless of the supported metal, showing that the support structure influences the prevalence of dehydration and oxidation pathways. The choice of metal nanoparticle influenced product selectivity along the oxidation pathway for both LaMnO3 and TiO2 supported catalysts. Au catalysts exhibited a higher selectivity to tartronic acid, whereas AuPt catalysts produced glyceric acid and Pt catalysts produced predominantly C–C scission products. [ABSTRACT FROM AUTHOR]

Published
2023
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45. A new class of Cu/ZnO catalysts derived from zincian georgeite precursors prepared by co-precipitation† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc04130b Click here for additional data file

Author

Smith, Paul J., Kondrat, Simon A., Chater, Philip A., Yeo, Benjamin R., Shaw, Greg M., Lu, Li, Bartley, Jonathan K., Taylor, Stuart H., Spencer, Michael S., Kiely, Christopher J., Kelly, Gordon J., Park, Colin W., and Hutchings, Graham J.

Subjects
Chemistry
Abstract

Zincian georgeite, an amorphous copper–zinc hydroxycarbonate, has been prepared by co-precipitation using acetate salts and ammonium carbonate., Zincian georgeite, an amorphous copper–zinc hydroxycarbonate, has been prepared by co-precipitation using acetate salts and ammonium carbonate. Incorporation of zinc into the georgeite phase and mild ageing conditions inhibits crystallisation into zincian malachite or aurichalcite. This zincian georgeite precursor was used to prepare a Cu/ZnO catalyst, which exhibits a superior performance to a zincian malachite derived catalyst for methanol synthesis and the low temperature water–gas shift (LTS) reaction. Furthermore, the enhanced LTS activity and stability in comparison to that of a commercial Cu/ZnO/Al2O3 catalyst, indicates that the addition of alumina as a stabiliser may not be required for the zincian georgeite derived Cu/ZnO catalyst. The enhanced performance is partly attributed to the exclusion of alkali metals from the synthesis procedure, which are known to act as catalyst poisons. The effect of residual sodium on the microstructural properties of the catalyst precursor was investigated further from preparations using sodium carbonate.

Published
2017

47. Preparation of a highly active ternary Cu-Zn-Al oxide methanol synthesis catalyst by supercritical CO 2 anti-solvent precipitation

Author

Kondrat, Simon A., Smith, Paul J., Lu, Li, Bartley, Jonathan K., Taylor, Stuart H., Spencer, Michael S., Kelly, Gordon J., Park, Colin W., Kiely, Christopher, and Hutchings, Graham J.

Abstract

Methanol synthesis using Cu/ZnO/Al2O3 catalysts is a well-established industrial process. Catalyst development is always an important factor and this has resulted in the current fully optimised commercial catalyst that is prepared by co-precipitation via hydroxycarbonate precursors. Recently, the synthesis of a CuZn hydroxycarbonate precursor, analogous to the rare mineral georgeite, was reported to produce a high activity methanol synthesis catalyst. Here we report the addition of Al3+, the third component found in industrial catalysts, to the zincian georgeite-derived catalyst prepared using a supercritical CO2 anti-solvent precipitation methodology. The co-addition of an AlO(OH) sol to the Cu/Zn precursor solution was found to not disrupt the formation of the CuZn georgeite phase, while providing efficient mixing of the Al3+ within the material. The catalyst derived from the CuZn georgeite precursor phase doped with Al3+ showed a high level of methanol synthesis productivity, which was comparable to that of the binary CuZn georgeite derived catalyst. This material also exhibited enhanced stability during an accelerated ageing test compared to the non-Al doped zincian georgeite material. Performance was benchmarked against an industrially relevant Cu/ZnO/Al2O3 standard catalyst.

Published
2018

49. Iron molybdate catalysts synthesised viadicarboxylate decomposition for the partial oxidation of methanol to formaldehydeElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2cy00699e

Author

Pudge, Geoffrey J. F., Hutchings, Graham J., Kondrat, Simon A., Morrison, Kate, Perkins, Eleanor F., Rushby, Alice V., and Bartley, Jonathan K.

Abstract

A series of iron molybdate catalysts were synthesised viaa sol gel route using either oxalic acid or malonic acid. Catalysts synthesised using malonic acid were found to give improved formaldehyde yields over those prepared using oxalic acid or a standard coprecipitation method. This was attributed to the iron and molybdenum malonate precursors forming discrete ions that when precipitated gave a homogeneous distribution of iron and molybdenum in the final catalyst. Metal oxalate precursors and materials synthesised using coprecipitation gave less homogeneous structures containing iron rich centres that led to combustion of methanol to carbon oxides.

Published
2022
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50. xNi–yCu–ZrO2 catalysts for the hydrogenation of levulinic acid to gamma valorlactone

Author

Jones, Daniel R., Sarwat Iqbal, Thomas, Liam, Ishikawa, Satoshi, Reece, Christian, Miedziak, Peter J., Morgan, David J., Bartley, Jonathan K., Willock, David J., Ueda, Wataru, and Hutchings, Graham J.

Abstract

We have investigated xNi–yCu–ZrO2 catalysts for the selective synthesis of γ-valerolactone from levulinic acid (LA). A series of xNi–yCu–ZrO2 catalysts with a consistent metal loading of 50% but varying Ni and Cu composition were prepared by an oxalate gel precipitation method and tested for LA hydrogenation. Ni-rich catalysts showed higher catalytic activity compared with Cu-rich formulations with a 45Ni–5Cu–ZrO2 composition yielding 76% γ-valerolactone after a reaction time of 30 min at 200 °C. Characterisation of the materials by XRD, surface area measurements and TPR allow us to attribute the differences in performance seen for different compositions to particle size and nanoparticle dispersion effects. DFT calculations also showed that a shift of d-band centre to higher energies with the mole fraction of Ni in Cu–Ni alloys would be expected to lead to improved hydrogen dissociation in Ni-rich catalysts and so aid hydrogenation activity.

Published
2018
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